From World Climate Report:
There is a bit of press covering a just-published paper that concludes that the current climate and ecological conditions in a remote lake along the north shore of Canada’s Baffin Island are unique within the past 200,000 years—and anthropogenic global warming is the root cause. Which of course, spells t-r-o-u-b-l-e.
Somehow, that temperatures there were several degrees higher than present for a good third of the past 10,000 years and that there has been virtually no temperature trend in the area during past 50 years—the time usually associated with the greatest amount of human-caused “global warming”—was conveniently downplayed or ignored.
The research team led by the University of Colorado’s Yarrow Axford, reconstructed the environmental conditions in and around the Baffin Island lake by tracking the behavior of various environmental proxies that they recovered from a long core sample extracted from the lake bottom.
Here is what they concluded that has managed to capture the attention of the press corps (a release from University of Colorado playing up this finding no doubt helped as well):
Paleoecological and geochemical data indicate that the past three interglacial periods were characterized by similar trajectories in temperature, lake biology, and lakewater pH, all of which tracked orbitally-driven solar insolation. In recent decades, however, the study site has deviated from this recurring natural pattern and has entered an environmental regime that is unique within the past 200 millennia. [emphasis added]
Figure 1 shows the summer (June, July August) average temperature from the weather station located at Clyde, Northwest Territory, which is located on Baffin Island very near the site of the lake. There is no trend here from 1943 to 2008, the period of available data. The most remarkable events are a couple of very cold summers and one very warm summer—all in the 1970s. Summers in the most recent decade are little different than summers in the 1950s—hardly a sign that human-caused “global warming” has made environmental conditions there particularly unique.
Figure 1. Summer (JJA) average temperature from Clyde, N.W.T. from 1953-2008 (data source: NASA GISS)
Well, perhaps the temperatures during the past 50 years or so are themselves unique in the past 200 millennia?
Figure 2 is a temperature history of the lake as derived by the authors themselves. We’ve added the horizontal red line which shows the authors’ determination of current lake water temperatures, as well as the two red circles which encompass periods during the past 200,000 years in which the lake’s water temperature was higher than current. The most recent one stretched from about 6,000 years ago to 10,000 years ago. The existence of this extended warm period during the early Holocene in this region is supported by other paleo-studies (e.g. Miller et al., 2005), so this result is nothing new.
Figure 2. Summer water temperature in the Baffin Island Lake inferred by the authors based on midge (mosquito-like insects)-assemblages. We’ve added the horizontal red line to indicate modern water temperatures, and the red circles to show periods during which the water temperatures were higher than modern values (adapted from Axford et al., 2009).
Given the history of temperatures in the region, both in the recent past and in the more distant past, is it hard to figure why any of this is particularly interesting.
However, here is what should have made the findings newsworthy:
The 20th century is the only period for which all proxies show trends consistent with warming despite declining orbital forcing, which, under natural conditions, would cause climatic cooling. The timing of this shift coincides with widespread Arctic change, including warming attributed to a combination of anthropogenic forcings that are unprecedented in the Arctic system. Thus, it appears that the human footprint is beginning to overpower long-standing natural processes even at this remote site. [emphasis added]
In other words, apparently, the human warming influence on the climate has managed to overcome the natural cooling trend which is trying to take us down into the next ice age and climate conditions which simply would not support a population of 6.5 billion (and growing) homo sapiens.
So, for those concerned about the human condition (which should seem to include most of us) this should come welcome and celebrated news.
Too bad the press isn’t interested in good news.
Axford, Y., et al., 2009. recent changes in a remote Arctic lake are unique within the past 200,000 years. Proceedings of the National Academy of Sciences, www.pnas.org_cgi_doi_10.1073_pnas.0907094106.
Miller G. H., et al., 2005. Holocene glaciation and climate evolution of Baffin Island, Arctic Canada. Quaternary Science Reviews, 24, 1703-1721.